Dental handpiece.



No. 834,899. PATENTED NOV. 6, 1906. W. W. FREEMAN. DENTAL HANDPIECE.

APPLICATION FILED AUG. 22. 1905'.

Fig

} WE11EBE51W.FIEEIZH'EIlwMM the armature 4 in the usual manner.

UNITED STATES PATENT OFFICE.

Specification of Letters Patent.

'Patented Nov. 6, 1906.

Application filed August 22, 1905. Serial No. 275.235.

To all whom it may concern.-

Be it known that I, WALLACE W. FREE- MAN, a citizen of the United States, residin at Norfolk, in the county of Norfolk and State of Vir inia, have invented certain new and useful Tm rovements in Dental Handpieces, of whic the following is a specification.

My invention relates to handpieces for dental drills, burs, and the like.

The object of m invention is to rovide a very light and sel -contained combined electric motor and handpiece for use in dental operations.

The further objects and advantages of the invention will be more fully set forth in this specification and then s ecifically pointed out in the claims annexed ereto.

The invention is shown in simple and convenient embodiments in the accom anying drawin s, forming a part of this speci ication,

in whicl 1 Figure 1 is a sectional elevation of the motor-shell with the handpiece and drill attached thereto. Fig. 2 is a diagrammatic view of the motor wiring and connections. Fig. 3 is a front view of the field-magnet ring or annulus with the notched cores forinin a part thereof. Fi 4 is an end view of t he spherical motor shell or casing, showing the pockets or depressions therein.

In the drawings like reference-numerals indicate similar parts in all the views.

1 is the dental hand iece, of any desired form, and is provided with a drill 1 or a bur and also has a slip or bayonet 'oint 2, so as to admit of its being removed om the motor-shaft when desired.

3 is a spherical shell or casing for the electric motor and is usually made of aluminium orother metal of low specific gravity in order to get li htness.

4 is tEe motor-armature, and 4, Fig. 3, is the armature-core, which consists of an aluminium cylinder, as shown in the fifgure.

5 is a continuous armature-she t and extends through the len th of the handpiece 1, and at one of its on s suitable provlsion is made to receive a drill, bur, or other instrument.

6 is the positive, and 7 is the negative, brush bearing upon the: commutator 7", through which the electric current is convoyedmto ie brushes 6 and 7 are usually inclosed in cylinders provided with springs, the cylinders being in the pockets or depressions 8 in the spherical casing 3, as shown.

9 is the lower, and 10 is the upper, fieldmagnet and are provided with ga s 10", Fig. 3, the magnets bein a part 0 t e ring 11, which is fastened to t e shell or casing 3 upon the shoulders 11 and 11 Fig. 1, and are suitably fastened by the bolts or screws 12 and 13. The gap or notches 10 concentrate the lines of force to the effective area of the magnet-cores, which is near the armature.

14 and 15 are the upper and lower fieldcoil and are removably fastened to the cores or magnets 9 and 10, so that they may be renewed, if necessary.

16, Fig. 2, is a wire from the lower brush 6 to one end of the s ring-switch 17, having a push-button 18 an a contact 18".

The switch or tongue 17 is normally in contact with the Z-shaped terminal 19, which is connected to an electric supply by the wire 20.

21 is insulation between the switch 17 and the spring contact-ton us 22, connected to the wire 23 and to t e resistance coil or rheostat 24, and from thence is attached to the negative feed-wire 23.

25 is a terminal button or contact having the Wire 26 in shunt across the rheostatcoil 24.

In the position shown in Figs. 1 and 2 the switch 17 is in its normal osition, the armature of the motor being s ortecircuited, and the motor is therefore not in o oration; but when the switch 17 is depresse the contact or point 18 comes in contact with the tongue 22, which places the rheostat in the circuit, and the motor will therefore rotate at a slower speed. When the switch 17 is further depressed, the s ring-tongue 22 is brought in contact with tlie button 25 and the motor will operate at full speed, the entire current passing through the wires 16 and 26 without traversing the rheostat.

In practice I arrange art of the connections and devices shown in Fig. 2 within the handpiece 1, the visible parts in that case being the switch 17, button 18 and the 2- she ed contact 19, as shown in Fig. 1.

I aving described my invention, what I claim, and desire to secure by Letters Patent, is-

1. In combination with a dental handpiece, an electric motor, a shaft driven by said motor passing through said handpiece having an armature thereon, a shell having a plurality of exterior ockets therein and covering said motor, a p urality of removable field-coils, a notched V-shaped ring core or pole piece for each coil, said cores forming a part of a ring, a resistance-coil in said shell, and means carried by the said handpieee for controlling said resistance.

2. in combination with a dental handiece, a motor, a shaft passin through the iandpiece in the direction of its length and carrym r an armature for said motor, a s )herical she l having a plurality of pockets therein, a spring-switch upon the said handpiece, a Z-shaped contact-piece normally bearing thereupon, an insulated spring-tongue beneath the said switch and adapted to make contact therewith, said switch and tongue having electrical connection with the motor and the source of electrical supply, a resistance-coil in circuit with said tongue, and a contact-button or terminal for contact with the tongue in shunt connection around said resistance from a supply-wire for operating the motor at full s )eed.

In testimony w iereof I have hereunto affixed my signature, in the presence of two witnesses, this 28th day of July, 1905.

WALLACE W. FREEMAN.

Witnesses:

WALTER B. Buanow, V. 'l. BURROW. 

